This invention relates to locks and more particularly to padlocks which may be unlocked either by a key or by a permutation mechanism.
A permutation padlock, more commonly known as a combination padlock, is a popular type of lock since it obviates the need for a key which the owner may not always have available when operation of the lock is required. The combination padlock is widely used in schools, athletic clubs and other similar institutions, and many times it is specified by the authorities of such institutions.
The usefulness and convenience of combination padlocks is somewhat diminished when, for whatever reasons, unlocking the padlock by the owner or some other authorized person is not possible since the combination of numbers needed to operate the combination mechanism is either not known or not readily available.
Centralized record keeping of the various number combinations for each lock is the usual means for overcoming this problem, but this is a cumbersome procedure and is also an added operating expense.
Accordingly, it is desirable to incorporate in the combination lock a key operated mechanism which can operate separately from the combination mechanism to open the padlock. A master key may be employed to accommodate all the combination locks in the institution or specified system.
Padlocks having both mechanisms, combination and key, for releasing the locking elements of the padlock are known in the marketplace. However, such a key mechanism is normally designed to function separately from the combination mechanism and it invariably involves operating elements that are complex in fabrication as well as in operation. Such dual locks are usually nothing more than two different locking mechanisms squeezed into one lock casing.
With the above background in mind, it is an object of the present invention to provide a dual combination and key padlock wherein the key controlled mechanism is incorporated in the combination mechanism whereby through either mechanism the lock may be opened.
Another object of the invention is to provide a dual combination and key padlock wherein the shackle of the lock is releasably engaged by a locking bolt, which bolt is releasable by operation of either the combination mechanism or the key mechanism.
A further object of the invention is to provide a dual combination and key padlock wherein the key mechanism is part of and integral with the padlock locking mechanism.
A still further object of the invention is to provide a dual combination and key padlock wherein the key mechanism is integral with a bolt releasably engaging the lock shackle and operable, in selective positions, to either release the bolt from engagement with the shackle exclusive of the operation of the combination mechanism, or move with the bolt when it is released from engagement with the shackle by operation of the combination mechanism.
A yet further object of the invention is to provide a dual combination and key padlock which is compact in construction, efficient in operation, and designed to be inexpensive in fabrication.